There was a time when investment banks were supposedly staffed by mercenary types who were only in it for the money. These people had limited allegiance to the banks they were working for, would leap from employer to employer in search of higher pay, and thought nothing of manipulating markets for their own benefit. Or at least, so suggested Marcel Rohner, the former chief executive of UBS, in his 2013 testimony to the UK House of Commons Select Committee on Libor manipulation. UBS had grown too quickly, said Rohner – it had hired too many ‘mercenaries’ from all over the place and interest rate fiddling was the result.

In theory, that’s all changed. Bankers are now locked into jobs by deferred bonuses. Unless they’re cutting costs, banks want to offer jobs for life. Goldman Sachs boasts that the average tenure of its managing directors is 12 years and rising. It’s all about creating ‘culture carriers’ and locking them down. – Except that our research suggests big banks are still heavily reliant on people they’ve recruited in the past three years,

We looked at staff registered with the UK Financial Conduct Authority (FCA) by three banks – Goldman Sachs International, JPMorgan Securities and Barclays Capital Securities. In each case, a high proportion of current staff have only been registered with each bank since 2011.

One third of all registered jobs in investment banks seem to be held by people hired in the past three years

Post-June 2011 registrations are highest at Barclays Capital Securities. There, the FCA Register shows that 36% of all UK-based registered staff were added in the past three years. At Goldman Sachs and JPMorgan, 34% of registrations have taken place over the same period.

Barclays declined to comment and Goldman Sachs and JPM didn’t immediately respond to our request for input into this article. The implication is that at each of these banks, one third or more of UK-based employees have been with the firm for less than 36 months. At Goldman Sachs International, 15% of staff have been registered within the past 12 months alone – compared to 13% at Barclays Capital Securities and 13% at JPMorgan Securities. Many of these newer hires are likely to be university and business school leavers. Banks are reliant on an army of youths.

What about the sagacious silverbacks who stay with the same firm forever? The FCA Register suggests they’re in small minority. At Goldman Sachs International, 16% of people were registered pre-June 2004. This falls to 15% at JPMorgan and a mere 5% at Barclays.

What does this say if you’re looking for a job in banking now? Firstly, that most banks continue to rely on an army of juniors. Secondly, that if you stick with one bank for longer than three years – and certainly for longer than five years – you’ll enter the ranks of the longest serving employees. Thirdly, if you stay with the same bank for a decade or more you’re a serious anomaly. Most banks still don’t offer jobs for life – or, at least, hardly any of their current staff are lifers (especially at Barclays).